204 Pennington — A Chemico-Physiological 



should be rich in suggestions for the explanation of the 

 life-history of higher types. 



The results of the investigation here offered are, in many 

 respects, incomplete. But it is believed that the work so 

 begun may suggest further study along the lines which are 

 here touched upon. 



The research was carried out under the direction of Prof. 

 John M. Macfarlane, of this university, and it gives me 

 pleasure to express my appreciation of his never-failing 

 kindness throughout the entire progress of the work. I 

 am also indebted to Prof. Edgar F. Smith, who has placed 

 at my disposal all the facilities of the John Harrison Lab- 

 oratory of Chemistry for the prosecution of the purely 

 chemical part of the research. 



Analysis of Spirogyra Nitida. 



For the analyses made during this investigation Spiro- 

 gyra nitida, in pure culture, was used. The material was 

 obtained from a pond in the Botanic Garden of the Uni- 

 versity which was singularly free from other species of the 

 genus. Some Elodca and a large water lily were the only 

 plants growing in the pond. The depth of water in the 

 deepest part was about four feet. The material was always 

 collected during the morning of clear days and was pre- 

 pared for use immediately. It was washed in running 

 water until any mud which might have adhered to the fila- 

 ments was removed. Distilled water served to free it from 

 all inorganic salts which the river water held in solution. 

 The clean threads were then laid on glass plates which 

 were inclined at a sharp angle, so that all water clinging 

 to the threads might run off. The threads were accepted 

 as dry when they assumed a light green color and their 

 individuality could be distinguished. 



In order to determine the water, dry substances, and ash 

 of Spirogyra, about sixty-eight grams of pure material were 

 dried at I io° C. until constant weight was obtained. It 

 was then found to have lost 89.94 per cent, of water. The 



